Cancer is diagnosed in more than 1 million people every year in the United States alone. In spite of numerous advances in medical research, cancer remains the second leading cause of death in the United States, accounting for roughly 1 in every four deaths. Although numerous treatments are available for various cancers, many forms of cancer remain uncurable, untreatable, and/or become resistant to standard therapies. For example, tumors may be inoperable because of their location or they may metastasize, making it difficult or impossible to treat the disease. Current therapies have considerable shortcomings. For instance, radiation therapy can cause damage to epithelial surfaces, swelling, infertility, fatigue, fibrosis, hair loss, dryness, and cancer. Chemotherapy can induce nausea, vomiting, diarrhea, constipation, anemia, malnutrition, hair loss, memory loss, depression of the immune system and hence infections and sepsis, hemorrhage, secondary neoplasms, cardiotoxicity, hepatotoxicity, nephrotoxicity, and otoxicity. Clearly the need for robust techniques to diagnose and treat cancer is manifest
Viruses have been shown to have tremendous utility in a variety of biomedical applications. Many of these techniques take advantage of the unique ability of viruses to enter cells at high efficiency. Some of these applications exploit viral gene expression and replication to induce expression of an inserted heterologous gene. It is well known that a variety of viruses deliver and express genes in cells (either viral or other genes), which may be useful, for example, in gene therapy, the development of vaccines, or cancer biology.
There is extensive literature on the use of viral vectors, particularly those based on adenovirus, adeno-associated virus (AAV), herpes virus and retrovirus, to increase the potency of anti-tumor therapy, however, these methodologies are in their infancy.